托福真題閱讀alaska and bark beetles答案及解析

托福真題閱讀alaska and bark beetles答案及解析

1.答題解析：答案:C；Subtle：微妙的。所以選C。

2.答題解析：答案:A；

此段講氣候的影響講了兩點：（1）As the length of the warm season increased over the 1980s and 1990s,however,bark beetles had more time to fly from one tree to the next,burrow,and lay their eggs between the bark and the wood.有更長的時間在樹木之間來回穿梭并產(chǎn)卵。（2）The beetles had another thing going for them,too:a multi-year drought had weakened many of the spruce trees,leaving them vulnerable to attack.使更多的數(shù)容易被攻擊和理由，綜合兩點來看，deposit its eggs in a greater number of trees是可能實現(xiàn)的，A對。BCD均無支持。

3.答題解析：答案:A；第二段講了spruce bark beetle epidemic in Alaska發(fā)生的過程，第三段講了是the effects of the bark beetle epidemic，有好有壞，BUT之前講的好的，BUT之后講的壞的，D肯定不對，因為BUT之后為意思中心講的是壞處。A講后續(xù)events，即為the effects of the bark beetle epidemic意思

4.答題解析：答案:B；The grasses,in turn,changed the soil temperature,making the environment more friendly for some other types of vegetation.Animals that feed on grasses,including moose,elk,and some birds,also benefited.顯然是B。

5.答題解析：答案是A和C；解析：Voles a type of small,mouselike rodent are an especially vital part of the ecosystem because they help spread mycorrhizal fungi,which attach to the roots of plants and help them take in water and nutrients.而現(xiàn)在Voles數(shù)量減少了，故C對D錯。Voles are also an important food for a number of predators.，現(xiàn)在Voles數(shù)量減少了，A對，B無體現(xiàn)。

6.答題解析：答案:B。轉(zhuǎn)折句，雖然ecosystem有恢復(fù)力，但是如果ALSKAN的生態(tài)系統(tǒng)被disturb太多，就可能恢復(fù)不了，而是變成另外一種生態(tài)系統(tǒng)。A只有“雖然”后的意思，沒有“但是”后所強調(diào)的重要信息，C的Alaska might again become covered with woodlands or grasslands與原文“但是”后的信息相反，D的信息有錯，原文說的是Alaskan spruce ecosystem是否能恢復(fù)，并非討論一般的ecosystems。B的話是對原句的轉(zhuǎn)述。

7.答題解析：答案:A；講One such example is the coral reef die-off that happened in the Indian Ocean in the late 1990s.【其中一個例子就是上世紀90年代末發(fā)生在印度洋的珊瑚礁滅絕。】是為了印證前面的In extreme cases,major assaults on ecosystems can lead to a total collapse in which the ecosystem doesn’t bounce back to the way it was or transition to a new,healthy state.The result is an area with very little life;in the oceans,biologists refer to these areas as dead zones.，【在極端情況下，對生態(tài)系統(tǒng)的重大攻擊可能導(dǎo)致生態(tài)系統(tǒng)的全面崩潰，無法恢復(fù)到原來的狀態(tài)或過渡到一個新的、健康的狀態(tài)。結(jié)果是一個幾乎沒有生命的區(qū)域;在海洋中，生物學家稱這些區(qū)域為死亡區(qū)?！匡@然為A。D錯在affected by a nearby dead zone

8.答題解析：答案:D；

ABC均無法回答，而第四段的In the short term,the Alaskan spruce beetle epidemic supplied a lot of people with firewood,but only by destroying tons of otherwise valuable timber and threatening the livelihoods of loggers.And no one knows for sure what the long-term impacts on the forest will be.【在短期內(nèi)，阿拉斯加云杉甲蟲的流行為人們提供了大量的柴火，但它摧毀了數(shù)噸原本很有價值的木材，并威脅到伐木工的生計。沒有人確切知道對森林的長期影響會是什么。】長期effects不知，但一些短期effects，如有更多的木柴，所以D對，這里說的是some of the effects，不一定要知道total effects.

9.答題解析：答案:C；

前文應(yīng)該提到this limited perspective，根據(jù)語境知指對人類的effects，即只看對人類的影響不看對整個生態(tài)的影響。后面要具體闡述為什么not completely straightforward。對應(yīng)C，C前面說focus on the impacts on a single species:for instance,us.，C之后說短期可能有益，長期對人類影響未知，有壞有好，長短期effects不一樣，故顯得not completely straightforward.

10.答題解析：答案:A B C；

D錯在epidemic in mycorrhizal fungi，原文講的是Voles數(shù)量變少，影響到mycorrhizal fungi的擴散，并非造成了mycorrhizal fungi因傳染病而亡。E的話，第四段說Ecosystem changes always hurt some living creatures and help others.It’s hard to say,therefore,whether a change is good or bad overall.。F的but after a transition period as a dead zone,they are able to return to their original state.沒有體現(xiàn)。A注意到第二段論點The biggest climate-caused ecosystem shifts today are happening at the world’s most northern latitudes,where the temperature over the last century has been rising about two times faster than the global average.B為第二段和第三段的概括，C為第四段和第五段的概括。

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